Specialty Materials, Inc.

Specialty Materials, Inc.


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Compression Behavior of High Performance Hy-Bor® and Graphite-Epoxy Bicycle Tubes
Dr. Al Kumnick (Specialty Materials, Inc.), Craig Calfee (Calfee Design)
and Tom Foltz (TuFF Materials Associates)


The use of boron fiber has come of age with its use in high performance road racing bicycles. The
weights of these bicycles have dropped from 18 pounds back in the 1980s to 14 pounds or less in
2005. Much of this weight savings comes with the use of carbon fiber composites. As bicycle
companies compete in the arms race for the latest materials to make even lighter bikes, safety and
durability are pushed to the limit. High modulus (55 Msi and greater) carbon fiber is being used to
make stiff yet thin walled tubing. These tubes can be vulnerable to damage from a variety of real
world sources. When slightly damaged from a pebble thrown up by a passing car, a thin walled tube
can rapidly degrade to an unsafe condition. Using boron filaments in the tube laminate can mitigate
this problem by allowing a slightly damaged tube to withstand continued use until noticed in a routine
inspection. This paper compares the damage tolerance of tubes made with intermediate modulus
(42 Msi) carbon fiber with thinner walled tubes made from a combination of boron and high modulus

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Aerospace Applications
F-16 Metal Matrix Landing Brace
Hy-Bor® Wing Cross Section Study
Space Structure Stabilization
Gas Turbine Engine Components

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